Solar battery module and manufacturing method therefor

ABSTRACT

A solar battery module and manufacturing method for a solar battery module having improved output are provided. The solar battery module  1  is a transparent substrate  10,  transparent resin layer  13   b,  solar battery cell  12,  colored resin layer  13   a  and back sheet  11  laminated in this order. The light-receiving surface  12   a  of the solar battery cell  12  faces the transparent resin layer  13   b  side. The backside  12   b  of the solar battery cell faces the colored resin layer  13   a.  The MFR [melt flow rate] of the transparent resin layer  13   b  is lower than the MFR of the colored resin layer  13   a.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of International Application PCT/JP2012/051149,with an international filing date of Jan. 20, 2012, filed by applicant,the disclosure of which is hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

The present invention relates to a solar battery module and amanufacturing method therefor.

BACKGROUND

In recent years, solar battery modules have received considerableattention as an energy source with a low environmental impact.

A solar battery module includes solar battery cells. These solar batterycells readily deteriorate when they come into contact with moisture.Because of this, solar battery cells must be isolated from outside air.Therefore, solar battery cells are usually arranged inside a fillerlayer provided between protective elements for protecting the front andback.

As described, for example, in Patent Document 1, this filler layer isprepared with colored EVA film in the portion positioned between thebackside of the solar battery cell and the protective element on thebackside. As described in Patent Document 1, the utilization efficiencyof light is enhanced by the use of colored EVA film. This can improvethe photovoltaic conversion efficiency.

CITED DOCUMENTS Patent Documents

Patent Document 1: Laid-Open Patent Publication No. 2003-258283

SUMMARY Problem Solved by the Invention

The solar battery module described in Patent Document 1 can bemanufactured by arranging a solar battery cell between colored EVA filmand transparent EVA film under heat and pressure to create a laminate.

However, when the solar battery module described in Patent Document 1 ismanufactured using this method, some of the colored EVA flows around tothe light-receiving side of the solar battery cell. When the colored EVAflows around to the light-receiving side of the solar battery cell, someof the light incident on the light-receiving surface is blocked by thecolored EVA. Because this reduces the light-receiving efficiency of thelight-receiving surface, the output of the solar battery module isreduced.

In view of this problem, it is an object of the present invention toprovide a solar battery module and manufacturing method for a solarbattery module having improved output.

Means of Solving the Problem

The solar battery module is a transparent substrate, transparent resinlayer, solar battery cell, colored resin layer and back sheet laminatedin this order. The light-receiving surface of the solar battery cellfaces the transparent resin layer side. The backside of the solarbattery cell faces the colored resin layer. The MFR [melt flow rate] ofthe transparent resin layer is lower than the MFR of the colored resinlayer.

In the manufacturing method for a solar battery module of the presentinvention, a laminate of a transparent substrate, transparent resinsheet, solar battery cell, colored resin sheet and back sheet is formedin this order. The light-receiving surface of the solar battery cellfaces the transparent resin sheet side. The backside of the solarbattery cell faces the colored resin sheet side. The transparent resinsheet has a viscosity greater than the viscosity of the colored resinsheet. The laminate is heated during lamination.

Effect of the Invention

The present invention is able to provide a solar battery module andmanufacturing method for a solar battery module having improved output.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of the solar cell module in anembodiment of the present invention.

FIG. 2 is a schematic cross-sectional view from line II-II in FIG. 1.

FIG. 3 is a schematic exploded cross-sectional view of the laminate.

DETAILED DESCRIPTION

The following is an explanation of preferred embodiments of the presentinvention. The following embodiments are merely illustrative. Thepresent invention is not limited to these embodiments.

Further, in each of the drawings referenced in the embodiments, membershaving substantially the same function are denoted by the same symbols.The drawings referenced in the embodiments are also depictedschematically. The dimensional ratios of the objects depicted in thedrawings may differ from those of the actual objects. The dimensionalratios of objects may also vary between drawings. The specificdimensional ratios of the objects should be determined with reference tothe following explanation.

FIG. 1 is a schematic plan view of the solar cell module in anembodiment of the present invention. FIG. 2 is a schematiccross-sectional view from line II-II in FIG. 1. As shown in FIG. 1 andFIG. 2, the solar battery module 1 includes a solar battery cell unit 2which has a transparent substrate 10 serving as the protective elementon the light-receiving side, a back sheet 11 serving as the protectiveelement on the back side, a filler layer 13 serving as the resin layer,and more than one solar battery cell 12.

The solar battery module 1 may be surrounded by a frame. A terminal boxfor extracting power may also be formed above the transparent substrate10 or back sheet 11.

(Transparent Substrate 10)

The transparent substrate 10 is arranged on the light-receiving surface12 a side of the solar battery cell 12. The transparent substrate 10protects the solar battery cell unit 2, and provides mechanical strengthto the solar battery module 1.

The transparent substrate 10 can be a glass plate or resin sheet.However, the transparent substrate 10 is preferably a glass plate. Glassplates have high rigidity and transparency to light, and areweather-resistant.

There are no particular limitations on the thickness of the transparentsubstrate 10. The thickness of the transparent substrate 10 may rangebetween 3 mm and 6 mm.

(Back Sheet 11)

The back sheet 11 faces the transparent substrate 10. The back sheet 11is arranged on the backside 12 b of the solar battery cell 12. The backsheet 11 can be a flexible resin sheet such as a polyethyleneterephthalate (PET) sheet. An inorganic barrier layer that isimpermeable to moisture, such as aluminum foil, may be provided on theinside of the resin sheet constituting the back sheet 11. The inorganicbattery layer also can be formed from an inorganic oxide such as siliconoxide, aluminum oxide, and magnesium oxide.

There are no particular limitations on the thickness of the back sheet11. The thickness of the back sheet 11 may range between 150 μm and 300μm.

(Solar Battery Cell Unit 2)

The solar battery cell unit 2 is arranged inside the filler layer 13.The solar battery cell unit 2 includes a plurality of solar battery cellstrings 3 that are electrically connected. A solar battery cell string 3has more than one solar battery cell 12. The solar battery cells 12 arearranged in one direction and are electrically connected in series or inparallel by wiring material 14. More specifically, the solar batterycells 12 are electrically connected in series or in parallel byelectrically connecting adjacent solar battery cells 12 using wiringmaterial 14.

Each solar battery cell 12 has a photoelectric conversion unit, and ap-side electrode and n-side electrode arranged on top of thephotoelectric conversion unit. The photoelectric conversion unitgenerates carriers such as electrons and holes from received light. Thephotoelectric conversion unit may have a crystalline semiconductorsubstrate of one conductive type, and a p-type amorphous semiconductorlayer and n-type amorphous semiconductor layer arranged on top of thecrystalline semiconductor substrate. The photoelectric conversion unitmay also have a semiconductor substrate with an exposed n-type dopantdiffusion region and a p-type dopant diffusion region on the surface.

The photoelectric conversion unit may also have a p-type or n-typecrystalline semiconductor substrate, a p-type amorphous semiconductorlayer and n-type amorphous semiconductor layer formed on top of thecrystalline semiconductor substrate, and an i-type amorphoussemiconductor layer of a thickness contributing hardly anything at allto the generation of electricity arranged between the crystallinesemiconductor and the p-type amorphous semiconductor layer and n-typeamorphous semiconductor layer.

Also, the solar battery cell 12 may be a so-called back junctionsolarbattery cell in which both the p-side electrode and n-side electrode arearranged on the backside of the photoelectric conversion unit.

There are no restrictions on the type of material used in the p-sideelectrode and n-side electrode provided it is a conductive material. Thep-side electrode and n-side electrode may be made of a metal such assilver, copper, aluminum, titanium, nickel or chromium, or an alloy ofthese metals. The p-side electrode and n-side electrode may also be alaminate with more than one metal and/or metal-alloy conductive layer.

(Filler Layer 13)

The filler layer 13 serving as the resin layer is arranged between thetransparent substrate 10 and the back sheet 11. The filler layer 13 isthe element used to seal the solar battery cell units 2. Therefore, thefiller layer 13 may also be called a sealing layer.

The filler layer 13 is a laminate including a colored resin layer 13 aand a transparent resin layer 13 b formed on top of the colored resinlayer 13 a. The solar battery cell unit 2 is arranged at the interfacebetween the colored resin layer 13 a and the transparent resin layer 13b. The solar battery cell unit 2 is arranged so that the light-receivingsurface 12 a of the solar battery cell 12 is facing the transparentresin layer 13 b side, and the backside 12 b is facing the colored resinlayer 13 a side.

In the present embodiment, the filler layer 13 serving as the resinlayer is a laminate of a colored resin layer 13 a and a transparentresin layer 13 b. However, there are no particular limitations on theresin layer of the present invention provided a colored resin layer ispositioned on the backside, and a transparent resin layer is positionedon the light-receiving side and adjacent to the colored resin layer. Theresin layer may have a resin layer other than a colored resin layer anda transparent resin layer. There may also be more than one colored resinlayer and transparent resin layer.

The transparent resin layer 13 b is arranged between the light-receivingsurface 12 a of the solar battery cell 12 and the transparent substrate10. Here, the transparent resin layer 13 b is a resin layer allowingpassage of light in the wavelength range used by the photoelectricconversion unit in the solar battery cell 12. The transparent resinlayer 13 b preferably has an average transparency of 85% or greater inthe 400 nm to 1,100 nm wavelength range.

The colored resin layer 13 a is arranged between the backside 12 b ofthe solar battery cell 12 and the back sheet 11. The colored resin layer13 a may be a resin composition including a resin and colorant. Thecolored resin layer 13 a may also be made of a colored resin such as awhite resin.

Specific examples of colorants include white colorants such as titaniumoxide particles or calcium carbonate particles, blue colorants such asultramarine, black colorants such as carbon black, and colorants thatmake the colored resin layer 13 a cloudy such as glass beads and otherlight-scattering materials. White titanium oxide particles arepreferably used as the colorant. When white titanium oxide particles areincluded in the colored resin layer 13 a, light is readily scattered bythe colored resin layer 13 a, and the photoelectric conversionefficiency of the solar battery module 1 can be improved.

In the present embodiment, the melt flow rate (MFR) of the transparentresin layer 13 b is lower than the MFR of the colored resin layer 13 a.In other words, the resin constituting the transparent resin layer 13 band the resin constituting the colored resin layer 13 a are combined sothat the melt flow rate (MFR) of the transparent resin layer 13 b islower than the MFR of the colored resin layer 13 a. The melt flow rate(MFR) of the transparent resin layer 13 b is lower than the MFR of thecolored resin layer 13 a preferably by 0.7 g/10 min. or more, and morepreferably by 1.0 g/10 min. or more.

More specifically, the resin constituting the transparent resin layer 13b is preferably one or more resins selected from a group includingethylenically unsaturated silane compounds, copolymers of ethylenicallyunsaturated silane compounds and α-olefins, and silane-modified resins.

Examples of ethylenically unsaturated silane compounds include vinyltrimethoxysilane, vinyl triethoxysilane, vinyl tripropoxysilane, andvinyl tricarboxy silane.

Examples of α-olefins include ethylene, propylene, 1-butene,isobutylene, 1-pentene, and 2-methyl-1-butene.

Examples of silane-modified resins include silane-modified ethylene,silane-modified urethane, silane-modified phenol, and silane-modifiedepoxies.

The resin constituting the colored resin layer 13 a is preferably one ormore resins selected from a group including ethylene-vinyl acetatecopolymers, ethylene-ethyl acrylate copolymers, silicone resins, epoxyresins, polyvinyl butyral, ethylene vinyl alcohol copolymers, acrylicresins, polyethylene, and polypropylene.

In the present invention, the melt flow rate (MFR) is the fluidity of amolten thermoplastic resin expressed as a numerical value.

The melt flow rate (MFR) can be calculated using the following method.An extrudate is sectioned at a fixed time interval, and the weight ofthe series of sections is measured, and the melt flow rate (MFR) isdetermined using Equation (1) below.

MFR (g/10 min.)=600×m/t  (1)

In Equation (1), MFR is the melt flow rate (g/10 min.), m is the averageweight of the sections, t is the time interval (sec.) at which the samewas sectioned, and 600 is the number of seconds in the reference time(=10 minutes).

(Manufacturing Method For Solar Battery Module 1)

The following is an explanation of an example of a method formanufacturing the solar battery module 1 with reference to FIG. 3.

First, as shown in FIG. 3, a laminate 30 is formed by laminating thetransparent resin sheet 22 constituting the transparent resin layer 13b, the solar battery cell unit 2, the colored resin sheet 21constituting the colored resin layer 13 a, and the back sheet 11 on topof the transparent substrate 10 in this order (laminate formation step).

Next, the laminate 30 is heated to complete the solar battery module 1(lamination step).

In the present embodiment, as mentioned above, the melt flow rate (MFR)of the transparent resin layer 13 b is lower than the MFR of the coloredresin layer 13 a. For this reason, the colored resin sheet 21 used inthe lamination process has a viscosity that is lower than that of thetransparent resin sheet.

When the laminate is laminated, the transparent resin sheet and coloredresin sheet become thinner at the edges of the laminate. Also, some ofthe transparent resin sheet and colored resin sheet at the edges of thelaminate flow towards the center of the laminate during the laminationprocess. The transparent substrate is relatively hard, and the resinsheet is flexible. As a result, the colored resin sheet provided on theresin sheet tries to flow towards the center of the laminate and towardsthe transparent substrate. This allows the colored resin sheet to flowaround to the light-receiving surface of the solar battery cell on theedges of the solar battery cell unit.

However, in the present embodiment, the MFR of the transparent resinlayer 13 b is lower than the MFR of the colored resin layer 13 a. Duringthe lamination process, the viscosity of the colored resin sheet 21 isalso lower than the viscosity of the transparent resin sheet 22.Therefore, colored resin sheet 21 trying to flow around to thelight-receiving surface 12 a of the solar battery cell 12 is stopped bythe higher viscosity transparent resin sheet 22. As a result, thecolored resin sheet 21 can be effectively prevented from flowing aroundto the light-receiving surface 12 a of the solar battery cell 12. Thus,a solar battery module 1 with improved photoelectric conversionefficiency can be manufactured.

In order to effectively prevent the resin of the colored resin sheet 21from flowing around to the light-receiving surface 12 a of the solarbattery cell 12, the MFR of the transparent resin layer 13 b (=the MFRof the transparent resin sheet 22) is lower than the MFR of the coloredresin layer 13 a (=MFR of the colored resin sheet 21) preferably by 0.7g/10 min. or more, and more preferably by 1.0 g/10 min. or more.

KEY TO THE DRAWINGS

-   1: Solar Battery Module-   2: Solar Battery Cell Unit-   3: Solar Battery Cell String-   10: Transparent Substrate-   11: Back Sheet-   12: Solar Battery Cell-   12 a: Light-Receiving Surface-   12 b: Backside-   13: Filler Layer-   13 a: Colored Resin Layer-   13 b: Transparent Resin Layer-   14: Wiring Material-   21: Colored Resin Sheet-   22: Transparent Resin Sheet-   30: Laminate

What is claimed is:
 1. A solar battery module comprising a transparentsubstrate, transparent resin layer, solar battery cell, colored resinlayer and back sheet laminated in this order; the light-receivingsurface of the solar battery cell facing the transparent resin layerside, the backside of the solar battery cell facing the colored resinlayer side, and the transparent resin layer having an MFR [melt flowrate] lower than the MFR of the colored resin layer.
 2. The solarbattery module according to claim 1, wherein the MFR of the transparentresin layer is lower than the MFR of the colored resin layer by 0.7 g/10min. or more.
 3. The solar battery module according to claim 1, whereinthe MFR of the transparent resin layer is lower than the MFR of thecolored resin layer by 1.0 g/10 min. or more.
 4. The solar batterymodule according to claim 1, wherein the transparent resin layercontains one or more resins selected from a group comprisingethylenically unsaturated silane compounds, copolymers of ethylenicallyunsaturated silane compounds and α-olefins, and silane-modified resins;and the colored resin layer contains one or more resins selected from agroup comprising ethylene-vinyl acetate copolymers, ethylene-ethylacrylate copolymers, silicone resins, epoxy resins, polyvinyl butyral,ethylene vinyl alcohol copolymers, acrylic resins, polyethylene, andpolypropylene.
 5. A manufacturing method for a solar battery modulecomprising: forming a laminate of a transparent substrate, transparentresin sheet, solar battery cell, colored resin sheet and back sheetlaminated in this order; the light-receiving surface of the solarbattery cell facing the transparent resin sheet side, the backside ofthe solar battery cell facing the colored resin sheet side, thetransparent resin sheet having a viscosity greater than the viscosity ofthe colored resin sheet, and the laminate being heated duringlamination.